Mount Prospect, Illinois 7 Day Weather Forecast

Wx Forecast - Wx Discussion - Wx Aviation

501
FXUS63 KLOT 311819
AFDLOT

Area Forecast Discussion
National Weather Service Chicago/Romeoville, IL
119 PM CDT Sun May 31 2026

.KEY MESSAGES...

- Some light showers or sprinkles possible tonight, most areas
  not likely to receive more than a couple of hundredths of an
  inch of precip.

- Generally dry conditions expected through much of the upcoming
  work week with the next appreciable rain chances not until
  Friday into next weekend.

&&

.DISCUSSION...
Issued at 119 PM CDT Sun May 31 2026

Strong high latitude blocking upper ridge over central Canada is
resulting in a rather wonky pattern with a WNW-ESE oriented
mid-upper level trough extending from the northern
Rockies/Pacific NW to the Cornbelt. Embedded lower amplitude
shortwaves, some convectively enhanced, are rounding the base of
this trough and running into the southern flanks of the upper
ridge. One such disturbance has been resulting in a band of
showers from northeast IA into central IL this afternoon. These
showers have been struggling to make any meaningful eastward
progress as they encounter a very dry easterly low level flow.
Can`t rule out a few light showers making into our far western
CWA very late this afternoon into this evening, though virga
seems to be the more likely outcome.

Tonight, weak low-mid level warm air advection to our west
associated with the aforementioned "sideways" upper trough
and some strengthening low-mid level cold air advection over the
western Great Lakes will result in a tightening of low-mid
level baroclinic zone from southern WI into northern IL. This
increased baroclinicity is most noted in the 850-700mb layer
where a strengthening frontogenetic circulation will likely
result in some moderately strong ascent. Air mass below this
f-gen circulation will remain very dry, so it will be a bit of a
battle to see whether or not the ascent with the frontogenesis
will be enough to penetrate the low level dry air mass.
Inherited chance of sprinkles tonight for most of the area and
this seems reasonable given the dry air and potential that
precip may not even reach the ground. One note of caution,
guidance does depict rather deep area of negative saturated EPV
near the vertical f-gen circulation. These type of set-ups can
sometimes overperform when, which could result in a narrow band
of showers heavy enough to wet the ground overnight.

Any showers/sprinkles late tonight should end by around or just
after sunrise with dry conditions expected much of the rest of
the week. Lake breeze, enhanced by synoptic northeast winds,
should result in a sizable footprint of lake cooled air Monday
through Wednesday. The most significant cooling relegated to
areas very near the lake.

The strong blocking ridge over Canada is progged to breakdown
later this week as a strong trough moves across far southern
Canada toward Hudson Bay by Friday. This should push the high
that`s provided the area with over a week of onshore flow to
move east and allow for southwesterly low level flow to develop
Thursday into Friday. This should advect a warmer and more humid
air mass into the area, likely including areas right up to the
lakefront both days. A cold front is likely to sag southward
across the western Great Lakes region Friday into Saturday with
increasing chances for at least periodic showers/storms. Some
variances emerge in the medium range guidance heading into the
weekend, but a more unsettled pattern could support at least
chances of showers and storms in the area through next weekend.

- Izzi

&&

.AVIATION /18Z TAFS THROUGH 00Z TUESDAY/...
Issued at 1212 PM CDT Sun May 31 2026

VFR with no significant concerns. Occasional sprinkles/light
rain may make it as far east as the Chicago metro terminals late
tonight into early Monday. With RFD having the best chance of
periodic -RA this evening and overnight, added in PROB30 mention
there. East-southeast winds inland and northeast winds near the
lake today will trend to a northeasterly directional area wide
on Monday.

Castro

&&

.LOT WATCHES/WARNINGS/ADVISORIES...
IL...None.
IN...None.
LM...None.

&&

$$

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